As is well known, in a polyphase AC rotary electric machine, harmonic currents must be controlled properly because the efficiency and output of the motor drops, and the torque ripple increases, if the space harmonics of the magnetic flux are large. Motor controls for selectively controlling the harmonic current components contained in the motor current are disclosed in Japanese Unexamined Patent Publications No. 2002-247899 and No. 2002-223600.
Japanese Unexamined Patent Publications No. 2002-247899 and No. 2002-223600 each propose a motor control apparatus which extracts a harmonic current component by high-pass filtering a first-order dq signal of the motor current, and controls the harmonic current through feedback by converting the extracted harmonic current component into a dq signal rotating synchronously with the specified order harmonic component of a rotating magnetic field.